Echo suppression and cancellation

When echo cancellation is called in the electronics, telecommunications and data transmission method for suppressing or eliminating echo or reverb effects in simultaneous transmission and reception (duplex ) of signals. In the telecommunications art, the echo canceller is also referred to as echo cancellation.

For example, the voice comes out of the speaker when making calls with hands-free again to the microphone and transmitted back. The person on the other end thus hears the echo of his own voice. The like may also be caused by induction or capacitive effects in the transmission data (crosstalk ) in the electric conductors and electronic components. To prevent this, the echo canceller is used.

Using special filters, a simple echo suppression (, echo cancellation ' ) can be achieved, but much better is the echo cancellation (, echo cancellation ' by subtracting the estimated echo signal ). Method for echo cancellation and noise suppression to be today mostly implemented in corresponding signal processors.

In the more general sense, the echo cancellation is a technique to separate the two directions of the duplex transmission signal over a common medium (e.g., the air of the listening room from the above example, the hands-free system or communication lines with ISDN).